ESR was founded in 1990 as a professional PA sound rental company. Shortly after we began producing custom made audio equipment. Carl Martin's goal was from the very beginning to develop and produce products for the demanding professional musician, with a superior sound quality and features not seen on any other guitar effect pedal. As a result of that our first guitar effect pedal, The Hot Drive’n Boost, was introduced in 1993. Due to our extensive knowledge of the professional music industry, and our contacts with a wide range of demanding musicians, we have been able to maintain a high quality of products and now have a range of 44 high quality guitar effect pedals, with more to come in the future. In 2005 we released our first point point handmade tube amplifier the Custom Shop 50, the line now includes heads,- cabs as well as a bass system.